The wearing of sunglasses, in particular in very bright light, is medically highly recommended for protecting long-term vision potential and also for safety reasons, for example when driving.
Specifically, sunglasses form a barrier to UV rays. Many studies have shown that UV rays may cause lesions, inflammations or deteriorations of the cornea, of the crystalline lens or of the retina. In order to prevent these effects and above all a modification of the eye which may reduce long-term vision, people are increasingly encouraged to wear sunglasses to prevent exposure to a too high light intensity.
Furthermore, sunglasses also make it possible to combat glare, which increases safety when driving or during sporting activities.
This is why sunglasses generally sold today block any radiation having a wavelength of less than 400 nm.
However, medical studies in recent years have shown that a wavelength range around 435 nm (±20 nm), also known under the name “bad blue light”, plays an important role, for example in age-related macular degeneration (AMD). This is a process which is cumulative over a lifetime and which becomes troublesome in particular for people over 60 years old.
In order to solve these problems, ophthalmic lenses are known that have filtering properties in the visible blue part of the spectrum between 400 nm and 480 nm.
However, these known ophthalmic lenses are not completely satisfactory in so far as a portion of the “good blue light” between 450 nm and 480 nm is also significantly attenuated, which is detrimental to the visual spectral perception of the sunglasses wearer. Furthermore, a deterioration of the contrast perceived by the user is observed, which may be a safety drawback, in particular for driving.